Antioxidant Properties and Hypoglycemic Potential of Genomically Diverse Bananas Cultivated in ...

102 Pages·2015·4.37 MB·English

Antioxidant Properties and Hypoglycemic Potential of Genomically Diverse
Bananas Cultivated in Southeastern United States

by

Gabriela A. Hernandez

A thesis submitted to the Graduate Faculty of
Auburn University
in partial fulfillment of the
requirements for the Degree of
Master of Science

Auburn, Alabama
August 1, 2015

Keywords: Musa, ethephon, physicochemical, ripening, maturity, antioxidant

Copyright 2015 by Gabriela A. Hernandez

Approved by

Floyd Woods, Chair, Associate Professor of Horticulture
Elina Coneva, Extension Specialist and Associate Professor of Horticulture
J. Raymond Kessler, Jr., Professor of Horticulture
Esendugue Greg Fonsah, Professor and Extension Specialist of Agriculture and Applied
Economics, University of Georgia, Tifton Campus, Tifton, GA 31793
Abstract

There has been increased interest in growing and selecting cold-hardy short-
season cultivars to offer an alternative to the industry standard, the Cavendish (genome
AAA). In addition to expansion of production, these specialty cultivars have advantages
such as increased nutritional qualities, resistance to disease, and favorable postharvest
attributes. The determination of suitable alternatives to the Cavendish subgroup is a
relatively new concept; therefore very little research has been done regarding the
postharvest and nutritional properties of these specialty cultivars.
The goal of the first experiment was to determine the effect of common
postharvest practices and length of storage on the quality and nutrition of specialty
bananas grown in the southeastern US. The objective of the second experiment was to
determine the effects of fruit maturity stage on antioxidant properties of short-season
cold-hardy cultivars. Results from both experiments indicate that genotype had role in
determining fruit physicochemical and antioxidant properties. Results of this study will
assist banana producers and commercial retailers in selecting adaptable cultivars, optimal
ripening stage and best management practices to enhance quality and nutritional content
of short season banana cultivars adaptable to southeastern United States.

ii
Acknowledgements

First, I would like to thank Dr. Floyd Woods for giving me the opportunity to
continue my education and pursue a career in post-harvest physiology. Without your
training, advice, encouragement, and patience, none of this would have been possible.
Thank you for all of your wisdom and positivity, and for always reminding me of the
importance of faith and family. I would also like to thank the members of my committee,
Dr. Elina Coneva, Dr. J. Raymond Kessler, and Dr. E. Greg Fonsah for all of your help,
support, and insight. Special thanks to the Alabama Nut, Fruit, and Vegetable Industries
for making this project possible. I’d like to give a huge “thank you” to Nicholas Larsen
for providing our samples during the second year of our trial and to Dr. Roland Dute for
allowing me to use your laboratory camera equipment. Thank you Michael Barnhill,
Camille Crosby, Jessica Bryars, and Nylan Holmes for all of your help in the laboratory;
I could not have done this without you.
I’d like to give a special thanks to my parents, Francisco and Idil Hernandez, for
your unwavering support and encouragement and for setting such a great example. I’d
also like to thank my brother Francis, who I was very lucky to have here with me these
past two years. You have no idea how much of a difference you made.
And finally, I’d like to extend my sincerest gratitude to Dr. Elizabeth Varriano-
Marston, Dr. James Finn, and "Maggie”. Thank you, Dr. Marston, for inspiring my
interest in post-harvest physiology and for giving me the confidence to further my
ii i
education. Without your guidance, encouragement, generosity, and support, I would not
be the person I am today. Thank you for always believing in me.

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Style manual or journal used:
HortScience: A Publication of the American Society for Horticultural Science

Computer Software used: Microsoft Word 2011, Microsoft Excel 2011, SAS v 9.3 and
SigmaPlot 13.

v
Table of Contents

Abstract....................................................................................................................... ii.
Acknowledgements..................................................................................................... iii.
List of Tables.............................................................................................................. viii.
List of Figures............................................................................................................. ix.
List of Abbreviations.................................................................................................. x.
Chapter I. Literature Review....................................................................................... 1
Chapter II. Effect of Artificial Ripening on Physicochemical and Antioxidant
29
Properties of Banana Fruit..........................................................................................

Abstract.................................................................................................................. 29
Introduction............................................................................................................ 30
Materials and Methods........................................................................................... 31
Results and Discussion........................................................................................... 37
Conclusions............................................................................................................ 46
Chapter III. Antioxidant Properties and Hypoglycemic Potential of Genomically
Diverse Bananas Cultivated in Southeastern United States........................................ 47
Abstract.................................................................................................................. 47
v i
Introduction............................................................................................................ 48
Materials and Methods........................................................................................... 52
Results and Discussion........................................................................................... 58
Conclusions............................................................................................................ 62
Chapter IV. Conclusions............................................................................................. 64
Chapter V. References................................................................................................ 66
Chapter VI. Appendices.............................................................................................. 78
Appendix A: Tables............................................................................................... 78
Appendix B: Figures.............................................................................................. 88

vi i
List of Tables

1. Physicochemical comparison assay means for ethrel treatments.................... 78

2. Ripening stages for Cavendish bananas as related to skin color and changes
in soluble starch and sugars............................................................................ 79

3. Post-harvest qualities of Grand Naine and Williams compared to FHIA-01
and FHIA-02 bananas..................................................................................... 79

4. Optimum Physicochemical Quality Parameters for Ripening Bananas.......... 80

5. Effects of storage time on peel ripening color index (RCI) and pulp dry
matter content of selected banana cultivars.................................................... 81

6. Effects of storage time on pulp pH and titratable acidity of selected
cultivars........................................................................................................... 82

7. Effects of storage time on pulp soluble solid content (˚Brix) of selected
cultivars........................................................................................................... 83

8. Effects of storage time on pulp vitamin C content of selected
cultivars........................................................................................................... 84

9. Interactive effects of maturity stage and genome on vitamin C, total
phenolics, and antioxidant capacity (FRAP VCEAC) in selected
cultivars........................................................................................................... 85

10. Main effect of cultivar on antioxidant capacity in selected cultivars.............. 86

11. Pearson’s correlation coefficients of antioxidant properties in banana pulp
at mature green, transitional, ripe, and over ripe stages.................................. 87

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List of Figures

1. Top 10 banana-producing countries compared to the United States in 2012
......................................................................................................................... 88

2. Global leading banana exporters by country in 2012...................................... 88

3. United States banana imports from 1990-2012............................................... 89

4. Control and Ethephon-treated selected cultivars after storage of 0, 3, 6, and
9 days in 20˚C and 90% RH............................................................................ 90

5. Selected cultivars at the mature green, transitional, and ripe stages............... 91

ix
List of Abbreviations

AA Ascorbic acid, reduced form
ABTS 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid)
ACP African, Caribbean and Pacific Group of States
C Celsius
˚ Degrees
DHA Dehydroascorbic acid, oxidized form
DPPH 2,2-diphenyl-1-picrylhydrazyl
EU European Union
FHIA Fundación Hondureña de Investigación Agrícola
FRAP Ferric reducing ability of plasma
FW Fresh weight
g Gram
GAE Gallic acid equivalent
GAEAC Gallic acid equivalent antioxidant capacity
gdw Grams dry weight
gfw Grams fresh weight
HAT Hydrogen atom transfer
kg Kilogram
L Liters
lb Pound
m Meters
MDA Malonydialdehyde
meq milliequivalents
MG Mature green maturity stage
1-MCP 1-methylcyclopropene
mg Milligram
mL Milliters
MPA m-phosphoric acid
OCA Overall cosmetic appearance
OR Over ripe maturity stage
% Percent
PAL Phenylalanine ammonia lyase
PCR Polymerase chain reaction
PPO Polyphenol oxidase
R Ripe maturity stage
x